Heated godet

ABSTRACT

Heated godets or rollers for the conveyance and heating of filaments or foils, especially of synthetic polymer material. Godets are operable at peripheral velocities at which the centrifugal force at the periphery is greater than the earth gravitational &#39;&#39;&#39;&#39;g&#39;&#39;&#39;&#39; and have hermetically sealed annular space partially filled with liquid.

United states Patent [72] lnventor Erich Lenk [56] References Cited kemscheid-benmp Germany UNITED STATES PATENTS 1 1 pp 8681399 69 2,739,218 3 1956 Wennerlund 219/469 1 Filed 3 3,020,383 2/1962 Onishi et a1 219/470 2?f2 2 Banner Mmhinenfabfik 3,135,319 6/1964 Richards 165/89 ssig e Akmngeseuschan 3,185,816 5/1965 Lusebrmk 219/471 Wuppertal, Germany Primary Examiner-Bemard A. Gilheany [32] Priority Oct. 24, 1968 Assistant Examiner-F. E. Bell [33] Germany Att0mey-Johnston, Root, OKeefie, Keil, Thompson & [31] P 18 04 777.3 Shurtlefi" [54] HEATED GODET Chums 6 Drawmg ABSTRACT: Heated godets or rollers for the conveyance and [52] US. Cl 219/469, heating of filaments or foils, especially of synthetic polymer 165/89 material. Godets are operable at peripheral velocities at which [51] Int. Cl Bllb 27/06 the centrifugal force at the periphery is greater than the earth [501 Field of Search 219/469, gravitational g and have hermetically sealed annular space partially filled with liquid.

PATENTE D FEB 9:971

SHEET 1 OF 2 INVENTOR ERICH LE(NK w kw r O K firv,

ATTORNEYS PATENTEDFEB slam 3,562,489 SHEET 2 OF 2 FIG.4

FIG 5 INVENTOR ERlCH LENK 1*, 074% .0 WW, L iQMLW i i i i Iii/Mill HEATED comzr INTRODUCTION Heated godets and rollers have been used already for many years in the textile industry. After the introduction of synthetic fibers they have been used preferably on textile machines in which such filaments, for example of polyamide or polyester, are subjected to a heat treatment, as, for example, in the stretching or texturizing. In the processing of synthetic threads and film bands, however, there frequently arises the requirement of maintaining very exact processing temperatures and very narrow temperature ranges. There are still, however, certain difiiculties in keeping uniform the surface or mantle temperatures over the entire width of the godet or roller. It is often found that even though the middle section of the godet has the desired temperature, the border or end zones lie below the desired or permissible temperature range. Even if it is possible, through suitable distribution of the heating power supplied in a certain operating state, to achieve a uniform temperature profile, this may change under other circumstances-for example, at other godet speeds or with other polymer material. Thus, for example, a filament running cold onto a heating godet and winding therearound a number of times can distort significantly the originally uniform temperature profile. The thread, initially cold relative to the godet, draws much heat energy from the'godet in the vicinity of the run-on point. As filament becomes warmer as it progresses spirally over the godet, it withdraws less and less heat from the godet surface. Even slight temperature differences make themselves noticeable at least in quality reductions which express themselves, for example, in the differing dyeability of the finished product. In order to comply with the requirements of practical use for uniform surface temperature of the godets or rollers, there have already been tried out the most diverse heating systems, such as, for example, electric resistance and inductive heating systems. There are also known heated godets in which a vapor or liquid medium is supplied externally over stuffing boxes or slide ring packings to the rotating roller or godet. The cost of manufacture of the latter godets, however, is high and their reliability in operation is low.

In German Utility Model Pat. No. 1,964,320 there is described an electrically heated roller which is constructed as a hollow body partially filled with liquid. The liquid is heated and then, in turn, the heat is transmitted uniformly to the wall of the roller. This functions, however, only when there occurs a relative movement between roller and liquid, i.e., at turning speeds at which the centrifugal forces are not so great that a closed liquid ring is formed by centrifugal force at the periphery. In the last case the liquid, which is a relatively poor heat conductor, acts like an insulating ring on the inside of the roller shell. It must be assumed that the liquid layer has sufficient depth so that the heating element is in direct contact with liquid itself. Otherwise the efficiency would be still less. The problem, namely the equalization of the godet surface temperature at high rotation speeds such as those at which the centrifugal acceleration is considerably greater than the earth gravitational acceleration, cannot be satisfactorily solved with such an apparatus.

Underlying the invention, therefore, is the problem of heating the godet or roller in such a way that even at high speeds, to every place on the outer, cylindrical surface-regardless of the amount of heat led off to the atmosphere or to the filament or foil to be heated-in each case such a quantum of heat is supplied automatically in a manner wherein the temperature of said surface remains virtually constant and substantially uniform.

DESCRIPTION OF THE INVENTION According to the present invention, the godet or roller cylindrical shell is double-walled cylinder with an annular hollow space between these walls. It is hermetically sealed to retain the liquid and its vapors. The inside face of the outer shell wall has projections extending radially inward into the vapor space and/or the outer face of the inner shell wall has projections extending radially outward, the radially outer ends of which are immersed in the liquid layer lying annularly by virtue of centrifugal force on the inside face of the outer shell wall. This construction of the godet or roller makes possible or favors the course of certain physical processes described further below, which positively bring about the uniform temperature distribution on the outer surface of the godet or roller. It is possible, therefore, to speak of an automatic regulation of the heat flux at every place on the cylindrical surface of the godet, in which connection it may be mentioned that this regulation has nothing to do with the regulation of the temperature level as such. 7

With observance of the prescribed features, the system can be constructed in various embodiments wherein a part or all of the projections extend substantially axially parallel or approximately axially parallel and have one or more interruptions or spaces serving as fluid passages in peripheral direction and/or part or all of the projections extend substantially in the peripheral direction and have interruptions or spaces serving as fluid passages in axial direction. Especially advantageous from the viewpoint of the manufacture and assembling of the godet or roller are those in which the projections of the inner and/or the outer shell wall having a spiral course, preferably with the aforesaid interruptions or spaces.

In view of the circumstances according to which the maximum heat supply from the heating element takes place in the middle zone of the cylindrical surface and the greatest heat dissipation takes place through the cylindrical wall at the axial end zones of the godet, the outer face of the inner shell wall can have radially outwardly extending projections mainly in the middle zone of the godet and the inner face of the outer shell wall can have radially inwardly extending projections mainly in the border zones of the godet or roller width.

In order to provide the necessary amount of heat for the vaporization of the liquid hermetically sealed in the annular spaces of the godet or roller, the shell walls of the godet or roller preferably are heated by a resistance or inductive heating device mounted stationarily in the interior of the godet or by a resistance heating device revolving with the godet or roller, to which the electrical energy can be supplied over slip rings. Especially from a construction viewpoint, the stationarily mounted inductive heating device has proved successful. In this connection it is advantageous for the efiiciency of the godet if, according to the invention, the shell walls, especially the inner wall, consist wholly or partially of material having good heat and electric conductance.

DESCRIPTION OF THE DRAWINGS In the drawings there are illustrated several preferred embodiments of the invention.

FIG. 1 is a diametric section of a first godet embodiment;

FIG. 2 is a half transverse section on section plane 2-2 of FIG. 1 without the heating element;

FIGS. 3 to 5 are diametric half-sections of additional godet embodiments of the invention; and

FIG. 6 is a half-transverse section on section plane 6-6 of FIG. 3.

PREFERRED EMBODIMENTS The godet according to FIGS. 1 and 2 consists essentially of a hollow cylinder formed by the substantially cylindrical, outer shell wall l, the substantially cylindrical inner shell wall 2, the disc-shaped end wall 3 which is connected in any expeditious manner to the drive shaft 4. Within the godet there is the heating element 5. The outer shell wall I has an axially parallel bore 6 which can receive a temperature measuring sensor which is connected in a manner known per se with a commercially known device (not shown) for the regulation of the electrical energy required for the energizing and/or controlling of the heating element. Furthermore, the inner face of the outer shell wall 1 has axially parallel ribs 7 circumferentially spaced thereabout. Into the longitudinal spaces between the ribs 7 there extend axially parallel ribs 8, which are provided on the outer face of the inner shell wall 2 and extend to close to the bottoms 9 of the spaces between the ribs 7 (FIG. 2). At the axially opposite ends of ribs 7 and 8 there are provided rings or grooves I and 11, serving as annular channels or manifolds.

The heating element can be a stationary electric-resistance or inductive heating element, which is attached by means of the collar 12 tothe machine frame. lf an inductive heating system is used, the heating body 5 is constructed as an electric winding with iron core, in which there is only a small air gap between the crosspieces of the iron core and the inner shell wall 2 in order to assure a good transition of the magnetic force lines into the shell walls 1 and 2 or through the inner shell wall 2 into the outer shell wall 1. Especially advantageous is a construction in which the middle section of the inner shell wall in the zone of the heating coil, therefore between the crosspieces of the coil-form core, consists of a metal capable of conducting heat and electricity well, for example, copper. This copper ring then acts as a short-circuited secondary coil with a winding in a transformer in which a relatively strong current flows, which is transformed into heat by the ohmic resistance of the ring.

In the assembly of the godet the shell walls 1 and 2 are interfit ed in such a way that they are substantially coaxial with substantially uniform spacings between the ribs 7 and 8. The shell walls 1 and 2 are so tightly connected with one another at the axial ends that the space resulting between them is hermetically sealed except for, at first, one or two bores through which the liquid heating medium, for example, water, is sup plied and the air is evacuated. Then these bores are sealed airtight. The amount of liquid provided in the space is great enough to assure that the radially outer ends 14 of the ribs 8 extend into the liquid layer 13, which is formed on the bottom 9 of the longitudinal spaces between the ribs 7 as the result of centrifugal force at rapid rotation.

In the heating of the godet, the liquid 13 begins to evaporate. Because of the evaporation, pressure and boiling point rise as the temperature becomes higher, until the required operating temperature of the godet outer shell is reached, as adjusted on the regulator. In a hermetically sealed space with a liquid and its vapor, there prevails a certain equilibrium between liquid amount and vapor amount or vapor pressure, which is determined by the temperature of the system. On supplying of heat to the water steam is formed; on withdrawal of heat, i.e., cooling of the vapor, this condenses again into water.

In order to make use of these physical processes, the godet must be designed in such a way that it favors these processes. Since the heating of the godet takes place from inside, i.e., over the inner shell wall 2, its projections or ribs 8 must extend radially outward to such an extent that they are immersed in the liquid 13 in order to impart by direct contact the amount of heat necessary for the evaporation. The projections or ribs 7 extending radially inward from the outer shell wall 1 into the vapor space, between liquid surface and shell wall 2, have the function of condensing the vapor on its surfaces and of conducting the liberated heat from the vapor space to the outer shell through the insulating liquid layer. ln detail, the follow ing takes place. At the outer godet shell heat is removed, both by the filaments and also by the surrounding air. Heat flows from inside the space via the ribs 7 radially outward, which ribs thereby themselves cool. Each ever-so-slight temperature drop below the equilibrium temperature in the liquid-vapor system on any surface which is in contact with this vapor has vapor condense thereon. The relatively great condensation heat liberated in the process is transferred outward over the ribs 7 to the shell wall 1. The greater the heat drop, the more rapid is the cbndensation. This is important especially in the places in which there exists the greatest heat requirement. The pressure drop at the places of condensation causes more vapor flow thereto. The centrifugal force throws the fresh condensate on the ribs against the space bottom 9. so that heat-insulating and vapor-barring liquid layers cannot gather in these places. Furthermore, the centrifugal force provides for a uniform distribution of the liquid, i.e., the liquid surface forms a cylinder concentric to the axis of rotation. The depth of liquid in the spaces between the ribs 7 is equalized by the interconnection of such spaces by the annular grooves 10 and l 1.

As the result of the above-described processes an equilibrium sets in automatically in every point constantly between discharged and supplied heat in such a way that the temperature over the whole length of the godet shell 1 remains virtually equal. Slight deviations of the surface temperature can be caused merely by the heat passage resistance of the outer godet shell. In places of greater heat flow, the temperature drop in the shell becomes greater.

The godet according to FIG. 3 differs from that according to FIGS. 1 and 2 in the execution and arrangement of the projections. The inner cylindrical shell wall 2a has circumferential projections or ribs 15 only in its middle section, which are provided by machining grooves 16 in the circumferential direction. These grooves are intersected by longitudinal grooves 17 uniformly distributed on the circumference. The cylindrical outer shell wall la has projections or ribs 18 only in the axially end zones, which are formed by machining of circular grooves 19 in the circumferential direction. These grooves are intersected also by several axially parallel grooves 20 distributed uniformly on the circumference (shown only in the right-hand end zone). The projections 18 and grooves 19 of the left end zone are formed in a ring 21, which is fitted into shell la after positioning the inner shell wall 2a into the outer wall Ia.

The projections 15 and I8 and the grooves 16 and 19 may be spirals. In this case it is possible to dispense with the ring 21, and instead the spiral groove 19 can be threaded into the corresponding shaped shell wall la. In the assembly, the inner shell wall 2a is simply screwed axially into the outer shell wall la. The addition of the liquid, the evacuating and the sealing of the hollow space between the shell walls 10 and 2a is carried out in the same manner as described above.

The equilibrium in the liquid-vapor system is fundamentally the same as in the godet illustrated in FIGS. 1 and 2. Since, however, experience has shown the heat discharge or loss is greatest near the axial ends of the godet, only at these ends are there provided projections or ribs 18 extending from the inner face of the outer shell wall on which the vapor can preferentially condense. In the axial midportion the condensation of the small vapor bubbles on the inner periphery of the outer shell wall suffices. These bubbles force their way through the thin liquid layer 13a in the narrow gap between the outer periphery of the projections or ribs 15 and the inner face of the outer shell wall In, namely, in places in which the temperature of the outer wall is lower. The liquid condensed on the projections or ribs 18 in the end zones in larger amounts can flow through the axially parallel grooves 20 back into the middle zone where it can evaporate again on the hotter projections or ribs 15.

In the embodiment of FIG. 4 the outer shell wall 17 can be constructed exactly like that of FIG. 3, i.e., it has circumferential projections or ribs 18 only at the axial ends. Theinner shell wall 2b has only axially parallel projections 23 in the middle section. For the manner of functioning of the liquid-vapor system in this godet there holds fundamentally what was stated for the embodiment according to FIGS. 1 and 2. To be sure, the course of the physical processes is promoted advantageously by this godet design. Since in the middle section of the shell lb there naturally prevails the greatest heat concentration, here the evaporation process is most intense and in the end zones of the godet the condensation process is most intense. correspondingly there are fonned pressure gradients from the middle to the ends which the vapor follows through the spaces between the ribs 23 to the projections 18.

H6. 5 shows a simplified or inexpensive construction in terms of ease of manufacture ofthe godet according to the invention. it has circumferential ribs or projections a only on one shell wall, preferably on the inner shell wall 2c. However, contrary to the embodiments hitherto described, part of the ribs or projections extend to the opposite shell wall 1c and lie firmly against it or are soldered to it for the achievement of a direct heat transfer. In the illustrated embodiment, the projections or ribs 25 of the axially end zones'so extend. The projections or ribs 25, like the projections 18 in FlGS. 3 and 4, have several axially parallel grooves 20 distributed on the periphery for the balancing of the liquid layer. Obviously the godets of FIGS. 3 to 5 have temperature measuring and regulating devices, the representation of which has-here been omitted.

It is thought that the inventionand its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several. parts without departing from thezspirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

lclaim:

l. A heated godet or roller for the conveyance and heating thereon of filaments, and particularly adapted for operation at high rates of rotation wherein the centrifugal force at the circumference is greater than the rate of earth gravitational acceleration, which comprises an outer shell having a cylindrical filament-conveying and heating surface, an inner shell within said outer shell with an annular space therebetween, means for hennetically sealing said annular space, a liquid partially filling said annular space whereby said liquidforms a circumferential layer on the inner face of said outer shell when said godet or roller is rotating at the aforesaid rate of rotation, the vapor portion of said liquid being between said layer of liquid and the outer face of said inner shell, and ribs on at lext one of said inner and outer faces extending respectively radially outwardly or radially inwardly from said faces with the respective radially outer or radially inner ends projecting respectively into said liquid layer or said vapor space.

2. A godet or roller as claimed in claim 1, means for heating I ;the inner shell, at least some of said ribs extending longitulayer to distribute substantially uniformly therein between said ribs.

3. A godet or roller as claimed in claim 1, means for heating said inner shell, and at least'some of said ribs extending circumferentially around said face or faces and axially extending grooves through said ribs providing communication in the longitudinal direction between said ribs.

4. A godet or roller as claimed in claim I, wherein said ribs on at least one of said inner and outer faces are spiral, circumferential ribs.

5. A godet or roller as claimed in claim I. wherein the longitudinal midportion of said outer wall of said inner shell has substantially parallel, longitudinally extending ribs thereon and said inner face of said outer shell has ribs extending radially inwardly from its inner face in the axial end portions of said godet or roller.

6. A godet or roller as claimed in claim I, and an electrical resistance or conductive heating means within said inner shell.

7. A godet or roller as claimed in claim I, wherein at least a portion of said inner shell wall is composed of a metal having high heat and electric conductance.

8. A godet or roller as claimed in claim I, wherein said outer face of said inner shell has circumferentially spaced, substantially axially parallel ribs with longitudinally extending grooves therebetween and the inner face of said outer shell has circumferentially spaced, substantially axially parallel ribs extending into said grooves. Y

9. A godet or roller as claimed ln'claim I, wherein said outer face of said inner shell has circumferential axially spaced ribs in the longitudinal midportion andsaid inner face of said outer shell has axially spaced circumferential grooves in the axial end portions thereof.

10. A godet or roller as claimed in claim 2, wherein said outer face of said inner shell has circumferentially spaced, substantially axially parallel ribs in the longitudinal midportion and said inner face of said outer shell has axially spaced circumferential grooves in the axial end portions thereof.

11. A godet or roller as claimed in claim 1, wherein said outer face of said inner shell has in the longitudinal midportion ribs extending radially outwardly therefrom with the radial outer ends spaced from said inner face of said outer shell, and ribs in the longitudinal end portions extending between shells. 

1. A heated godet or roller for the conveyance and heating thereon of filaments, and particularly adapted for operation at high rates of rotation wherein the centrifugal force at the circumference is greater than the rate of earth gravitational acceleration, which comprises an outer shell having a cylindrical filament-conveying and heating surface, an inner shell within said outer shell with an annular space therebetween, means for hermetically sealing said annular space, a liquid partially filling said annular space whereby said liquid forms a circumferential layer on the inner face of said outer shell when said godet or roller is rotating at the aforesaid rate of rotation, the vapor portion of said liquid being between said layer of liquid and the outer face Of said inner shell, and ribs on at least one of said inner and outer faces extending respectively radially outwardly or radially inwardly from said faces with the respective radially outer or radially inner ends projecting respectively into said liquid layer or said vapor space.
 2. A godet or roller as claimed in claim 1, means for heating the inner shell, at least some of said ribs extending longitudinally on at least one of said faces in circumferentially spaced, substantially axially parallel relationship, and circumferential passages in said annular space to allow said liquid layer to distribute substantially uniformly therein between said ribs.
 3. A godet or roller as claimed in claim 1, means for heating said inner shell, and at least some of said ribs extending circumferentially around said face or faces and axially extending grooves through said ribs providing communication in the longitudinal direction between said ribs.
 4. A godet or roller as claimed in claim 1, wherein said ribs on at least one of said inner and outer faces are spiral, circumferential ribs.
 5. A godet or roller as claimed in claim 1, wherein the longitudinal midportion of said outer wall of said inner shell has substantially parallel, longitudinally extending ribs thereon and said inner face of said outer shell has ribs extending radially inwardly from its inner face in the axial end portions of said godet or roller.
 6. A godet or roller as claimed in claim 1, and an electrical resistance or conductive heating means within said inner shell.
 7. A godet or roller as claimed in claim 1, wherein at least a portion of said inner shell wall is composed of a metal having high heat and electric conductance.
 8. A godet or roller as claimed in claim 1, wherein said outer face of said inner shell has circumferentially spaced, substantially axially parallel ribs with longitudinally extending grooves therebetween and the inner face of said outer shell has circumferentially spaced, substantially axially parallel ribs extending into said grooves.
 9. A godet or roller as claimed in claim 1, wherein said outer face of said inner shell has circumferential axially spaced ribs in the longitudinal midportion and said inner face of said outer shell has axially spaced circumferential grooves in the axial end portions thereof.
 10. A godet or roller as claimed in claim 2, wherein said outer face of said inner shell has circumferentially spaced, substantially axially parallel ribs in the longitudinal midportion and said inner face of said outer shell has axially spaced circumferential grooves in the axial end portions thereof.
 11. A godet or roller as claimed in claim 1, wherein said outer face of said inner shell has in the longitudinal midportion ribs extending radially outwardly therefrom with the radial outer ends spaced from said inner face of said outer shell, and ribs in the longitudinal end portions extending between and in direct contact with said inner and outer faces of said shells. 